The nations Tyre wanted to trade with would instead attack her, prepared for war. Like Jerusalem, she would become loot for their armies.
as the sea brings up its waves: This image fits Tyre very well. Tyre was built on a small island along the coast. Waves were a normal part of life there.
The picture shows how enemies would strike Tyre again and again, like waves hitting the shore. It is a metaphor (a word picture) for a military assault.